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THURSDAY, June 21, 2012 (HealthDay News) — New research may help answer the age-old question of whether factors such as the weather or drinking red wine can set off a migraine.

According to research presented this week at the annual meeting of the American Headache Society in Los Angeles, both of these factors can trigger the excruciating headaches, but not for all people and not all the time.

One small study looked at 33 adults in Brazil who considered themselves regular red-wine drinkers and believed that the beverage had caused migraines in the past. All were asked to drink half a bottle (375 milliliters) of a Malbec, Tannat, Cabernet Sauvignon and Merlot wine from South America at least four days apart.

Although most participants reported having a migraine at least once within 12 hours of drinking wine, some wines were more to blame than others — specifically Tannat and Malbec. Both varieties contain higher levels of flavonoids known as tannins, which provide red wine's rich coloring.

Although the study was not a controlled one, conceded study lead author Dr. Abouch Krymchantowski, "I concluded that the wines with the highest content of tannins — Tannat and Malbec — are those which triggered migraines more frequently."

People who point to red wine as a migraine trigger but still like to drink it should choose wines with the lowest tannin content, added Krymchantowski, who is director and founder of the Headache Center in Rio de Janeiro.

"It's a small study, but it confirms what we hear from patients: Wine can trigger migraines, but not necessarily all the time," said Dr. Brian Grosberg, an assistant professor of neurology at Albert Einstein College of Medicine and co-director of the inpatient headache program at Montefiore Headache Center in New York City.

Krymchantowski would now like to see data on whether wines from different regions — Australia and France, for example — would behave differently in people who suffer migraines.

A second study being presented at the meeting found that outside temperature also can trigger migraines, especially among people who are more sensitive to temperature.

Sixty-six migraine patients were asked to keep a headache diary over the course of a year. Temperature change was linked with mild headaches 21 percent of the time, but only 5 percent of the time for more severe headaches.

And the association seemed more closely linked to cold rather than hot days.

"The study provides pioneering evidence that headaches are associated more with temperature among those with subjective temperature sensitivity than those without," said study lead author Dr. Shuu-Jiun Wang, deputy head of the Neurological Institute at Taipei Veterans General Hospital and a professor of neurology at National Yang-Ming University School of Medicine in Taipei, Taiwan.

"If patients report temperature sensitivity, physicians should pay more attention and may adjust preventive agents in certain seasons ... for these patients," he added.

This study, too, confirms patients' accounts and even previous research findings that a rise in temperature increased the incidence of headaches, said Grosberg, who was not involved in either study. But often it's not just one factor that starts a migraine attack, but two or more together.

"Sometimes it's one strong trigger, but usually it's a combination of two or more triggers that will precipitate an attack," Grosberg said.

Triggers could include menstrual cycles, lack of sleep, inclement weather and changes in barometric pressure.

It's not clear from these studies if other triggers may have played a role in the onset of migraines, Grosberg said.

Research presented at medical meetings should be viewed as preliminary, because it does not undergo the scrutiny given to studies published in peer-reviewed journals.